This invention relates to the recovery of oil from subterranean oil reservoirs and, more particularly, to an improved waterflooding operations involving the use of ultrasound technique to improve oil recovery.
Cross reference is made to the following applications filed concurrently herewith: Attorney Docket Number D/A0026 entitled xe2x80x9cProcess lo And Apparatus For Obtaining Ink Dispersions By Subjecting The Liquid Inks To An Ultrasonic or Sonic Signalxe2x80x9d, Attorney Docket Number D/A0026Q1 entitled xe2x80x9cA Method For Removing Trapped Impurity Aggregates From A Filterxe2x80x9d, Attorney Docket Number D/A0026Q2 entitled xe2x80x9cMethod For Dispersing Red And White Blood Cellsxe2x80x9d, Attorney Docket Number D/A0871 entitled xe2x80x9cAn Ultrasonic Method For Improving Cleaning And Redispersal Of Saturated Particle Aggregates In Processes Using Liquid Inksxe2x80x9d, Attorney Docket Number, Attorney Docket Number D/A0870 entitled xe2x80x9cAn Ultrasonic Method For Speeding The Drying Of Fluid Saturated Images In Processes Using Liquid Inksxe2x80x9d, and Attorney Docket Number D/A0998 entitled xe2x80x9cMethod For Manufacturing Processxe2x80x9d.
M. A. Biot, J. Acoust. Soc. Am. 28,168 (1956).
M. A. Biot, J. Acoust. Soc. Am. 28 179 (1956).
M. A. Biot, J. Appl. Phys. 33, 1482 (1962).
D. L. Johnson, T. J. Plona, and H. Kojima, J. Appl. Phys. 76(1), 115 (1994).
T. J. Plona, R. D""Angelo, and D. L. Johnson, xe2x80x9cVelocity and attenuation of fast, shear, and slow waves in porous mediaxe2x80x9d, in IEEE 1990 Ultrasonics symposium Proceedings, Vol 3, B. R. McAvoy editor. IEEE, N.Y. (1991), 1233-1239.
J. E. White, Seimic waves: radiation, transmission, and attenuation, McGraw-Hill book Company, New York, N.Y., 1965, pg. 70.
J. C. Williams, The packing of solid Particles, Chapman and Hall, Ltd. London, England, 1968, pg 34.
In the recovery of oil from oil-bearing reservoirs, it is usually possible to recover only minor portions of the original oil in place by the so-called primary recovery methods which utilize only the natural forces present in the reservoir. A variety of supplemental recovery techniques have been employed in order to increase the recovery of oil from subterranean reservoirs. The most widely used supplemental recovery technique is waterflooding which involves the injection of water into the reservoir. As the water moves through the reservoir, it acts to displace oil therein to a production system composed of one or more wells through which the oil is recovered.
It has long been recognized that factors such as the interfacial tension between the injected water and the reservoir oil, the relative mobilities of the reservoir oil and injected-water, and the wettability characteristics of the rock surfaces within the reservoir are factors which influence the amount of oil recovered by waterflooding. It has been proposed to add surfactants to the floodwater in order to lower the oil/water interfacial tension and/or alter the wettability characteristics of the reservoir rock. Processes which involve the injection of aqueous surfactant solutions are commonly referred to as surfactant waterflooding or as low-tension waterflooding, the latter term having reference to the mechanism involving the reduction of the oil-water interfacial tension. Also, it has been proposed to add viscosifiers such as polymeric thickening agents to all or part of the injected water in order to increase the viscosity thereof, thus decreasing the mobility ratio between the injected water and oil and improving the sweep efficiency of the waterflood.
An object of the present invention is to improve waterflooding operations involving the use of ultrasound technique to improve oil recovery. There is provided a method for recovering oil from a subterranean formation including injecting an aqueous composition into said formation and displacing said oil toward one or more production wells; subjecting the aqueous composition to an ultrasonic signal to release oil from the formation; and removing the aqueous composition containing oil from said one or more production wells.